Xanthandrus (Xanthandrus) nitidulus Fluke
Xanthandrus (Xanthandrus) nitidulus Fluke, 1937.
Fluke, C.L.,Jr. (1937) New South American Syrphidae (Diptera). American Museum Novitates 941, 14 pp.
Xanthandrus (Xanthandrus) nitidulus Fluke, 1937.
Fluke, C.L.,Jr. (1937) New South American Syrphidae (Diptera). American Museum Novitates 941, 14 pp.
This genus is very close to Melanostoma Schiner, 1860, but it differs from this by possessing larger size of the body and the abdomen elliptic, wide and flat, arista bare, central portion of the epistoma moderately proeminent, face narrow and longer and wider styles. While Melanostoma has arista sometimes pubescent, not proeminent epistoma, terminalia with a style thin, straight and uniform, reduced metasternum, legs of males narrow, without bristles, and without patterns of hair or modified piles (from Borges and Pamplona 2003).
The most significant morphological characters to separate Xanthandrus specimens are: postpronotum bare, face and scutellum black, metaepisternum with some fine subappresses pile; metacoxa with a pile tuft at posteromedial apical angle; and antennal pits confluent.
X. nitidulus has the face, in the middle, golden pollinose and lateral margin white pollinose; pleura golden pollinose; wings with costal and subcostal cell pigmented. Abdomen of the male and female with similar yellow maculae on 2nd to 4th terga, or also on 5th tergum.
Adapted from Borges and Pamplona (2003).
MALE.
Head: Vertical triangle shiny black with brown pile; ocellar triangle golden pollinose; frontal triangle white pollinose; antennal tubercle black; lunule brown, reddish laterally; central prominence black to brown; face, in the middle, golden pollinose and lateral margin white pollinose, both with brown and golden piles; gena brown. Antenna with scape, pedicel and basal and inferior third of the basoflagellomere reddish brown, 2/3 remaining of the basoflagellomere brown to black; arista brown.
Thorax: Scutum shiny black with golden pollen, covered with golden pile; postalar callus brown; pleura black with golden pollen; dorsomedial and posterior anepimeron shortly pubescent; katepimeron on all extension pilose; katatergum pubescent to pilose; calypter light yellow with golden pile; halter entirely yellow, or darker on capitulum; posterior spiracle yellow surrounded by concolor pile. Legs, in general, light brown, basal and apical third of the tibiae and femur-tibial articulations yellow, covered with brown ground-cover pile; procoxa with brown pile surrounding the apical margin; mesocoxa with row of brown pile on anterior surface and metacoxa with long yellow pile. Wing with microtrichia except on basal half of the br, bm and CuP cells; costal and subcostal cells with yellow pigmentation.
Abdomen: Brown with yellow pile and with a pair of yellow maculae, semicircular on 2nd tergum, trapezoid on 3rd tergum and triangular on 4th tergum, or also small lateral triangular maculae on 5th tergum. Genitalia: Surstylus curved with apical concavity on internal surface; aedeagus apodeme narrow broadening at apex and almost not overtaken the hypandrium.
FEMALE.
Similar to the male, differing as follows: Abdomen differing on shape of the macula of the 3rd tergum that is approximately rectangular. Genitalia: Hypoproct round and with two discal lack of pigmented areas; epiproct with bristles in the intern surface of each plate; 8th tergum with a 'M' shape pigmented area; spermathecae with granulations.
Length: body, 11-12 mm; wing, 10 mm (Borges and Pamplona 2003).
Xanthandrus has been considered member of the tribe Bacchini sensu lato, although some phylogenetic analysis suggest that Baccha is the only memeber of Bacchini and the other genera commonly related to them should be included in the tribe Melanostomini. Rotheray and Gilbert (1989, 1999) included Melanostoma and Xanthandrus, which, in their analysis, were isolated from the other genera of the ‘‘traditional’’ Bacchini by the tribe Syrphini. These authors also suggested the tribe Melanostomini with only Melanostoma and Xanthandrus as Palaearctic members.
Neotropical species known from Argentina and Brazil.